Doozer (https://github.com/ha/doozerd) got me excited. It's small, fast, and written in Go. Unfortunately, its development seems quiet and fragmented. Its lack of TTL-style values made it a pain to do a distributed lock service without having a sweeper for cleaning up dead locks.
Zookeeper (http://zookeeper.apache.org) is much more fully featured and mature, but felt way too heavy compared to my nimble Go stack. Installing and maintaining a JVM just for Zookeeper made me uncomfortable.
Etcd is interesting. It has TTLs, it's small and fast, easy to pick up/learn, and it's in active development (and it's tied with CoreOS and Docker, so it's bound to get some reflected love).